SAN DIEGO -- Another foggy start across parts of San Diego County Wednesday prompted forecasters to again urge drivers to use extra caution through the morning commute.
A National Weather Service dense fog advisory for the coast and valleys is set to remain in effect until 9 a.m. Forecasters said the fog may cause visibility along roadways in the valleys and along the coastline to suddenly drop to a quarter mile or less at times.
"Low clouds and fog have reduced visibility near the coast and there are areas of dense fog mainly on the mesas and higher coastal terrain," according to the weather service. "The weather today will be very much as it was yesterday -- fair with some coastal clouds and fog."
Forecasters advised motorists traveling through foggy areas to give themselves extra time to reach their destinations, use extra caution in dense fog, slow down and use low-beam headlights. The fog is expected to clear after 8 a.m.
Over the next couple days, a ridge of high pressure slowly breaking down will slightly deepen the marine layer, which will cause the clouds to extend farther inland each night, and will bring cooler weather throughout the county, according to the NWS.
Mountain and desert wind in the afternoon and evenings is also expected later this week, ahead of a cold front forecasters predicted would bring rain, mountain snow and strong winds this weekend into early next week as the ridge of high pressure moves off to the east.
"Things will begin to change over the weekend as the ridge slides eastward, allowing the core of the jet stream to position itself off the West Coast," according to the weather service. "This shift in the broad scale weather pattern will finally open the door for more active weather along the West Coast. Rain and mountain snow will develop in Southern California Sunday into Monday with significant precipitation possible."